Abstract: A method for optical stress analysis comprises the steps of directing an incident beam of polarized light to the sample to be analyzed and analyzing a light bundle exiting the sample in two detection channels extending perpendicular to one another with respect to the polarization direction, providing that the incident beam is elliptically polarized, carrying out the elliptical polarization with an elliptic shape having a comparatively large ratio of the large principal axis to the small principal axis, the direction of rotation of the elliptical polarization of the incident beam changing periodically and using two alternative states of the direction of rotation for each measurement process, adjusting the detection channels which extend perpendicular to one another corresponding to the position of the principal axes of the ellipse and carrying out the difference between two measurements consecutively with the same beam intensity of the incident beam and the same ratio of principal axes, but with opposite direc

Abstract: A method for optical stress analysis comprises the steps of directing an incident beam of polarized light to the sample to be analyzed and analyzing a light bundle exiting the sample in two detection channels extending perpendicular to one another with respect to the polarization direction, providing that the incident beam is elliptically polarized, carrying out the elliptical polarization with an elliptic shape having a comparatively large ratio of the large principal axis to the small principal axis, the direction of rotation of the elliptical polarization of the incident beam changing periodically and using two alternative states of the direction of rotation for each measurement process, adjusting the detection channels which extend perpendicular to one another corresponding to the position of the principal axes of the ellipse and carrying out the difference between two measurements consecutively with the same beam intensity of the incident beam and the same ratio of principal axes, but with opposite direc

Abstract: The invention is directed to a method and an arrangement for the response analysis of semiconductor materials with optical excitation. The object of the invention, to find a new type of response analysis of semiconductor materials with optical excitation which also allows a sufficiently precise detection of the charge carrier wave with a higher excitation output and a shorter charge carrier lifetime, is met according to the invention in that an exciting laser beam is intensity-modulated with two discrete modulation frequencies (.OMEGA..sub.1 ; .OMEGA..sub.2), the luminescent light exiting from the object is measured on the difference frequency (.OMEGA..sub.1 -.OMEGA..sub.2), and the luminescent light is analyzed as a function of the arithmetic mean (.OMEGA.) of the modulation frequencies (.OMEGA..sub.1 ; .OMEGA..sub.2). The invention is applied in the semiconductor industry for determining different electrical parameters of semiconductor materials.

Abstract: A process and arrangements for photothermal spectroscopy (thermal wave analysis) by the single-beam method with double modulation technique. A single-beam method is developed making use of the advantages of double modulation technique in detecting the photothermally generated difference frequency without requiring partial beams and while achieving extensive absence of intermodulation, the intensity of the laser beam is modulated before striking the object in such a way that the modulation spectrum substantially contains a carrier frequency (f.sub.1) and two sideband frequencies (f.sub.1 .+-.F.sub.2), wherein f.sub.2 is the base clock frequency of the modulation, a regulating detector and a control loop intervening in the modulation process suppress that component of the base clock frequency (f.sub.2) in the same phase with the mixed frequency of the carrier frequency and sideband frequencies.

Abstract: A method and apparatus for thermowave analysis employs a single laser beam, which has an additive, two-frequency, intensity modulation, and is directed onto the object. The amplitude of the mixed frequency of the discrete modulation frequencies, which is not contained in the exciting beam, is analyzed as response signal. By obtaining a reference signal from the exciting beam and forming the difference between this exciting beam and the measurement signal, noise suppression and a lowering of the limit of sensitivity are achieved in an advantageous manner.